The overall goal of this project is to study, by biochemical techniques, the novel proteins that are produced after infection of Escherichia coli with the T-even bacteriophages. Previous work led to discovery of the enzyme T4 exonuclease A and also mutants of phage T4 deficient in the ability to induce T4 exonuclease A, T4 endonuclease 11, and nuclear disruption of the host nucleoid. The objectives of this project include (a) enzymic, physiological, and genetic characterization of mutants deficient in T4 exonuclease A, and (b) biochemical and physiological studies on the process of nuclear disruption.